This invention relates to a photosensitive composition and a pattern forming process using such composition.
The interior side of the face plate of the color picture tube is coated with three different kinds of phosphor in dots or in stripes. This phosphor coat layer is formed in the following way. First, a mixed coating material composed of a phosphor for the first color and a photosensitive resin is applied on the interior side of the face plate and dried to form a coating film, and this layer is irradiated with ultraviolet rays through the holes in a shadow mask. The ultraviolet rays are irradiated to the position where the electron beams for effecting emission of light from the phosphor hit, that is, the place where said phosphor is to be attached. The photosensitive resin at the irradiated portion is insolubilized, resulting in insolubilization of the entire layer in that portion. Then the layer is washed with a solvent, retaining the insolubilized portion alone on the face plate while removing the other portion of the layer by dissolution. Then the same operation as said above is performed with the layer formed from a mixture of a phosphor for the second color and a photosensitive resin, and this is followed by the same operation by using a mixture of a phosphor for the third color and a photosensitive resin.
As appreciated from the foregoing explanation, the color picture tube phosphor surface forming process is complicated, and multiple times of repetition of wet coating, water washing and drying are required, so that simplification of such process is quite desirable.
As an improvement on such process, some of the present inventors have previously proposed, in Japanese Laid-Open Patent Application No. 126861/78, a method of forming the color picture tube phosphor surface in a considerably simpler manner than the prior art. This method was attained on the basis of a new finding that the photolytic product of an aromatic diazonium salt has an ability to accept powder particles, and it is characterized by (1) coating the inner surface of the face plate of a corlor picture tube with a photosensitive composition containing an aromatic diazonium salt as a photosensitive component and getting sticky by light exposure, thereby forming a thin coating layer on said surface, (2) subjecting said thin layer to patternwise exposure to make the exposed portion sticky, and (3) contacting the powder particles with the exposed thin layer to have said powder particles accepted by said thin layer.
According to this method, mere repetition of exposure and powder contact is required for the phosphors of the second and third colors, and when the coating film is once formed, it is possible to form as many phosphor patterns as desired. It is also possible to produce a black matrix by using powder of a light-absorbing material such as, for example, carbon powder.
This method, however, has a drawback that the processing time is rather long due to a somewhat lower sensitivity of the photosensitive component than the conventional photosensitive resins.
On the other hand, the following references are also known to show the state of the art: British Pat. Nos. 1,103,864 and 1,103,865.